Functional inorganics and ceramic additive manufacturing

ABSTRACT

The present disclosure relates to systems, methods and resins for additive manufacturing. In one embodiment, a method for additive manufacturing of a ceramic structure includes providing a resin including a preceramic polymer and inorganic ceramic filler particles dispersed in the preceramic polymer. The preceramic polymer is configured to convert to a ceramic phase. The method includes functionalizing inorganic ceramic filler particles with a reactive group and applying an energy source to the resin to create at least one layer of the ceramic phase from the resin.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/065,324 filed Oct. 17, 2014, the entire contentsof which are incorporated herein by reference thereto.

BACKGROUND

The present disclosure relates to additive manufacturing and, moreparticularly, to systems, methods and resins for additive manufacturingof ceramic phase structures.

Fabrication of ceramic parts for high-temperature applications usingconventional methods is difficult. By way of example, some materials aredifficult and expensive to machine due to hardness. Machining canrequire extended periods of time for dense materials. In addition, itmay be especially challenging to use conventional methods to providecomplex geometries and similarly to produce particular shapes.

There is a need for systems and methods of preparing components fromdense material and similarly for producing components of hightemperature applications.

BRIEF DESCRIPTION

Disclosed and claimed herein are systems, methods and resins foradditive manufacturing of ceramic structures. One embodiment is directedto a method for additive manufacturing of a ceramic structure, themethod including providing a resin, the resin including a preceramicpolymer and inorganic ceramic filler particles dispersed in thepreceramic polymer, wherein the preceramic polymer is configured toconvert to a ceramic phase, and wherein the inorganic ceramic fillerparticles are functionalized with a reactive group and configured toconvert to the ceramic phase. The method also includes applying anenergy source to the resin to create at least one layer of the ceramicphase from the resin.

In one embodiment, the preceramic polymer is polycarbosilane.

In one embodiment, the ceramic phase is silicon carbide.

In one embodiment, the inorganic ceramic filler particles arefunctionalized with a reactive group.

In one embodiment, the energy source is a laser source for curing atleast one of the preceramic polymer and ceramic filler particles.

In one embodiment, the resin is provided in a bath for additivemanufacturing.

In one embodiment, the inorganic ceramic filler particles includefunctional groups configured to decompose and a ceramic phase, whereinthe ceramic phase remains during fabrication.

In one embodiment, applying an energy source to the resin includes freeform fabrication of a three-dimensional article formed of siliconcarbide.

The method further includes processing an article formed by the layerand one or more additional layers by at least one of thermal, plasma,microwave and radiative curing, and curing methods in general.

Another embodiment is directed to a system for additive manufacturing ofceramics, the system including a bath configured to contain a resin, theresin including a preceramic polymer and inorganic ceramic fillerparticles dispersed in the preceramic polymer. The preceramic polymer isconfigured to convert to a ceramic phase, and the inorganic ceramicfiller particles are functionalized with a reactive group and configuredto convert to the ceramic phase. The system also includes an energysource proximate to the bath, and a controller coupled to the energysource and configured to apply the energy source to the resin to createat least one layer of the ceramic phase from the resin.

Another embodiment is directed to a resin for additive manufacturing ofceramics, the resin including a preceramic polymer wherein thepreceramic polymer is configured to convert to a ceramic phase andinorganic ceramic filler particles dispersed in the preceramic polymer,wherein the inorganic ceramic filler particles are functionalized with areactive group and configured to convert to the ceramic phase.

In one embodiment, the ceramic phase is silicon carbide

Other aspects, features, and techniques will be apparent to one skilledin the relevant art in view of the following detailed description of theembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the present disclosure willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 depicts a simplified system diagram according to one or moreembodiments;

FIG. 2 depicts a graphical representation of particle functionalizingaccording to one or more embodiments;

FIG. 3 depicts a process for additive manufacturing according to one ormore embodiments; and

FIG. 4 depicts a process for providing functionalizing particlesaccording to one or more embodiments.

DETAILED DESCRIPTION Overview and Terminology

One aspect of the disclosure relates to additive manufacturing, and inparticular, to additive manufacturing using functionalized particles.One embodiment is directed to a resin including a preceramic polymer andfunctionalized particles. Other embodiments are directed to systems andmethods for additive manufacturing with functionalized particles, suchas functionalized inorganic particles. In an exemplary embodiment,silicon carbide (SiC) powder is functionalized (e.g., modified) suchthat the surface of the silicon carbide powder particles arefunctionalized with a chemical group that has the ability to convert toa non-oxide ceramic of choice and to interact selectively with an energysource. In that fashion, the functionalized surface of the particles canbe cured or energized to react by laser light and thermally postprocessed to have a silicon carbide containing structure.Functionalization also includes adding a binding material to the powder.According to one embodiment, functionalization of the powder is adifferent step from buildup and curing of a structure.

In addition to functionalizing particles, another aspect is to provide aresin that will convert to a ceramic phase of choice.

As used herein, ceramic phase relates to a solid state and structurehaving homogeneous physical and chemical characteristics.

Preceramic polymer relates to a pre-cursor for the fabrication ofsilicon based ceramic.

Inorganic ceramic filler particles are particles or powders. Theinorganic ceramic filler particles can be dry or in suspension with theresin.

Reactive group elements relate to surface components configured toprovide binding of silicon based ceramic particles.

Photosensitive group elements relate to surface components configured toprovide binding of silicon based ceramic particles and which are curedby a photo source.

As used herein, the terms “a” or “an” shall mean one or more than one.The term “plurality” shall mean two or more than two. The term “another”is defined as a second or more. The terms “including” and/or “having”are open ended (e.g., comprising). The term “or” as used herein is to beinterpreted as inclusive or meaning any one or any combination.Therefore, “A, B or C” means “any of the following: A; B; C; A and B; Aand C; B and C; A, B and C”. An exception to this definition will occuronly when a combination of elements, functions, steps or acts are insome way inherently mutually exclusive.

Reference throughout this document to “one embodiment,” “certainembodiments,” “an embodiment,” or similar term means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. Thus, the appearancesof such phrases in various places throughout this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner on one or more embodiments without limitation.

Exemplary Embodiments

Referring now to the figures, FIG. 1 depicts a simplified system diagramof system 100 according to one or more embodiments. System 100 may beconfigured for additive manufacturing of ceramics using a curable resin.By way of example, system 100 may employ functional inorganics toproduce ceramics using a laser scanning process, such asstereolithography (SLA) or alternately using light emitting diodes(LEDS) or lasers in digital light processing (DLP). System 100 includescontroller 105, energy source 110, platform 120, and bath 125.

Controller 105 is coupled to energy source 110 and configured to controlapplication of the energy source 110 to the resin 130 to create at leastone layer of the ceramic phase from the resin. Application of energysource 110 includes generation of laser, shown as energy source beam115, which may be employed to form a layer of the ceramic phase in orderto generate three-dimensional structures. Energy source 110 may be alaser source for curing or reactively bonding at least one of thepreceramic polymer and ceramic filler particles. Energy source 110 maybe one or more of a light (e.g., photo), ultraviolet (UV), infrared(IR), e-beam source or other available regions of the electromagneticspectrum. System 100 may include the use of multiple beams or more thanone energy source. For example, in certain embodiments, system 100 mayinclude one or more energy sources to provide different energies tointeract with the resin. Energy source 110 may be positioned proximateto the bath 125 and resin 130, such as above and/or near the resin 130,for application of at least one of a beam and the source to resin 130.

Platform 120 may be adjusted by elevator 140 to position one or moreformed layers relative to energy source 110. The position of platform120 may be controlled by controller 105.

Bath 125 is configured to contain and/or hold a resin 130, such as acurable resin, including a preceramic polymer and inorganic ceramicfiller particles dispersed in the preceramic polymer. In one embodiment,the ceramic filler particles are functionalized with a photosensitivegroup. In another embodiment, the preceramic resin is functionalizedwith a reactive group. According to another embodiment, catalysts can beused to enhance the curing or reactivity of the functional group. Resin130 is provided in a bath 125 for additive manufacturing. In oneembodiment, resin 130 is a liquid suspension. According to anotherembodiment, resin 130 is a slurry of inorganics. Resin 130 can includeinorganic ceramic filler particles that include functional groupsconfigured to decompose and a ceramic phase, wherein the ceramic phaseremains during fabrication of the three-dimensional structure. Accordingto another embodiment, resin 130 is a nanofluid.

In one embodiment, system 100 is configured to build three dimensionalceramic structures, such as silicon carbide structures. As such, thepreceramic and ceramic phase may be selected to generate siliconcarbide. To that end, in one embodiment, the preceramic polymer ispolycarbosilane and the ceramic phase is silicon carbide. The resin 130may be configured at a molecular level to convert to a ceramic phase, orother phase of choice, such as ceramic phases suitable for hightemperature applications. For example, to create a silicon carbide part,system 100 can employ a preceramic polymer that thermally converts tosilicon carbide, such as a polycarbosilane or modified polycarbosilane.In one embodiment, resin 130 would be slurry filled with ceramic fillerparticles that are uniformly dispersed in the resin 130. By way ofexample, a silicon carbide particle is chemically functionalized with areactive group, such as a photo-sensitive group that can also convert toa desirable ceramic phase such as SiC. The functionalized SiC particleswould be created in slurry form and energy source 110, which may be alaser-based SLA-type system, is configured to cure the slurrylayer-by-layer so that a three dimensional solid would be constructed.Upon removal of unsolidified resin or slurry, the ‘green ceramic body’could be further post-processed by exposure to one or more of thermal,plasma, microwave, and other radiative methods.

When excited by energy source 110 and energy source beam 115, thepolycarbosilane component of resin, such as resin 130, may form anamorphous, partially crystalline or crystalline structure of siliconcarbide. Application of energy source 110 to the resin 130 includes freeform fabrication of a three-dimensional article formed of siliconcarbide. In one embodiment, application of laser beam 115 to resin 130,and in particular resin surface 135, at least partially converts thepreceramic polymer and ceramic filler particles to a ceramic phase, suchas silicon carbide.

According to one embodiment, structures formed by system 100 may befurther processed by at least one of thermal, plasma, microwave andradiative exposure, and curing methods in general.

Although the discussion of system 100 refers to silicon carbide, itshould be appreciated that other inorganics and ceramic polymers may beemployed by the system for additive manufacturing.

System 100 may be configured to build and fabrication dense, monolithicceramic parts for high temperature turbine applications. System 100 mayadditionally allow for fabrication of complex geometries from hard andbrittle materials by additive manufacturing. In addition, system 100 mayallow for direct fabrication of engineering ceramics using resin-basedadditive manufacturing methods including direct fabrication ofengineering ceramics useful for turbine components.

FIG. 2 depicts a graphical representation of particle functionalizingaccording to one or more embodiments. According to one embodiment,inorganic particles may be functionalized prior to addition to a resin(e.g., resin 130). FIG. 2 depicts an inorganic particle 205, which maybe silicon carbide. Particle 205 and additional inorganic particles arefunctionalized shown as 210, with reactive group elements, such asphotosensitive group elements shown as 211. Functionalized particle 215is shown including particle 205 and a plurality of photosensitive groupelements 211. Functionalized particles may be distributed and dispersedin a preceramic polymer, such as a polycarbosilane liquid.Functionalized particle 215 may be a functionalized inorganic particle.According to one embodiment, the extent and composition of functionalitycan be tailored. In certain embodiments, functionalized particle 215 maybe formed of functional groups that intentionally decompose to leavebehind desirable ceramic phases, such as silicon carbide.

According to one or more embodiments, exemplary reactive group elementsfor functionalizing may include one or more of silyl, halo, haloformyl,hydroxyl, alkyl, alkenyl, alkynl, carboxamido, carbonyl, oxo, amino,azo, benzyl, amido, carboxyl, cyanato, imino, keto, nitro, peroxy,phenyl, phosphate, phosphoro, sulfonyl and sulfo, as well as short chainstructures containing one or more such functional groups. According toone or more embodiments, exemplary photosensitive group elements includearyl azides, halogenated aryl azides, azoquinones, cinnamoyl groups,benzophenones and, anthroquinones. According to one or more otherembodiments, particles, such as particle 205, may be between 100nanometers and 250 microns in average diameter. In other embodiments,particles, such as particle 205, may be between 200 nanometers and 100microns in average diameter. In yet another embodiment, particles, suchas particle 205, may be between 500 nanometers and 50 microns in averagediameter. Particle size distributions particle 205 can be mono-, bi- ormulti-modal. According to one embodiment, functionalization ofparticles, such as particle 205, converts relatively unreactive, benignsurface of the starting particle to that of a reactive, convertiblesurface. According to one embodiment, the functionalized particle 215may be cured or reacted together, shown by 225 to form a layer 230.Layer 230 may be a cured network layer of functionalized silicon carbideceramic particles, as would be found in a single build layer of a 3-Dvolumetric build. Functional groups are bonded to other functionalgroups or particles and may have partially converted to ceramicphase(s).

One or more additional layers may be formed to layer 230 for additivemanufacturing or buildup, shown as 235 to form a three-dimensionalobject 240. Build up 235 may be an iterative build up of layers viastereolithography or digital light processing. Three-dimensional object240 represents a silicon carbide ceramic structure from functionalizedparticle 215 and resin (e.g., resin 130). Three-dimensional object 240may be post processed and/or machined following a build process.

According to one embodiment, inorganic particles may be functionalizedand dispersed in a resin for additive manufacturing. FIG. 2 depictssilicon carbide as an exemplary inorganic particle. However, it shouldbe appreciated that one or more other types of particles may beemployed, including but not limited to oxides, non-oxides, carbides,nitrides, oxycarbides, oxynitrides, borides, phosphides, etc. Althoughthe description of FIG. 2 relates to silicon carbide, the systems andmethods described herein may employ exemplary inorganics such as one ormore of SiC, Si₃N₄, B₄C, SiCN, SiOC, HfC, AlN, BN, ZrO₂, SiO₂, Hf0 ₂,Al₂O₃, B₂O₃, yttrium silicate and disilicate, and the like, and mayrelate to mixtures thereof.

FIG. 3 depicts a process for additive manufacturing according to one ormore embodiments. Process 300 may be initiated at block 305 withproviding a resin (e.g., resin 130) with functionalized particles (e.g.,functionalized particle 215). The resin is provided to include apreceramic polymer and inorganic ceramic filler particles dispersed inthe preceramic polymer. The preceramic polymer is configured to convertto a ceramic phase, such as silicon carbide. In one embodiment, thepreceramic polymer of FIG. 3 is polycarbosilane. Polycarbosilanes andmodified polycarbosilanes may be characterized as having a structuralbackbone including silicon-carbon and can produce silicon carbide onpyrolysis or controlled decomposition. Similarly, polysiloxanes may becharacterized by a silicon-oxygen backbone and produce siliconoxycarbides on pyrolysis.

The inorganic ceramic filler particles are functionalized with areactive group, such as inorganic ceramic filler particles 215 andconfigured to convert to the ceramic phase. The inorganic ceramic fillerparticles include functional groups configured to decompose and aceramic phase, wherein the ceramic phase remains during fabrication. Inone embodiment, the functionalized particles are uniformly dispersed inthe resin. The resin may be provided in a bath for additivemanufacturing.

At block 310, one or more layers may be formed/built by applying anenergy source to the resin to create at least one layer of the ceramicphase from the resin. Applying an energy source to the resin includesfree form fabrication of a three-dimensional article formed of siliconcarbide. The energy source may be a laser source for curing at least oneof the preceramic polymer and ceramic filler particles. By way ofexample, a “green body” may be formed at block 310.

For example, if silicon carbide is the desired ceramic phase,polycarbosilane may be employed as the preceramic polymer.Polycarbosilane is a liquid polymer with silicon carbon binding, theaddition of heat will convert the polymer to silicon carbide withextensive shrinkage, but ultimately can produce amorphous, partiallycrystalline or fully crystalline silicon carbide. According to oneembodiment, a resin or resin slurry can be provided by combining apreceramic polymer and functionalizing of silicon carbide powder. Onelayer of the resin or resin slurry may be provided with a laser orenergy beam of an energy source to draw the structure of choice. Anotherlayer of resin would then be provided, followed by repeated exposure toan energy source. In this manner, a three-dimensional structurecontaining resin, which may be partially converted to ceramic, andfunctionalized silicon carbide filler would be constructed. Thisstructure then has the ability to be processed by heat later on tocreate more silicon carbon structure. Thus, silicon carbide powder in amatrix of silicon carbide are created by the polymer. The polymer, whichmay be cured resin plus silicon carbide filler, is part of the build up.

At block 315, the formed structure may be cured or reacted. Curing orreaction may include heating and/or applying pressure to a formedarticle. Curing or reaction may include exposing a formed article to aparticular atmosphere composition. As a result of the curing, articlesmay be hardened and/or shrink.

Process 300 may optionally include post-processing of the formedstructure at block 320. Processing at block 320 may include one or moreof the an article formed by the layer and one or more additional layersby at least one of thermal, plasma, microwave, exposure to anotherelectromagnetic energy source, and radiative curing, and curing methodsin general. Anything not cured could be removed. In addition, postprocessing of the article with heat would create more silicon carbidefrom the structure. After heat treating, articles may be post processedby importing more resin into any voids of the 3D structure.

FIG. 4 depicts a process for providing functionalized particlesaccording to one or more embodiments. According to one embodiment, aresin is based on curable preceramic polymer, wherein the resin iscurable by one or more of a light (e.g., photo), UV, IR, e-beam or otherenergy source. Process 400 depicts a process for providing a resin. Inone embodiment, process 400 is initiated at block 405 with receivinginorganic particles, such as an inorganic powder. Process 400 includesbonding reactive group elements to the inorganic particles at block 410.For example, inorganic ceramic filler particles are functionalized atblock 410 with a photosensitive group. The reactive group elementsand/or the inorganic ceramic filler particles are configured to convertto the ceramic phase, such as silicon carbide.

Functionalizing allows for a binder to be introduced with inorganicparticles. With respect to silicon carbide powder, the particles willhave silicon carbon bonding. According to one embodiment, anothersilicon containing species, such as silane-based coupling agent, may bechemically bonded to the silicon carbide powder. The bondingfunctionalizes the surface of the particles including a reactive orphotoactive functional group, which in turn produces a modified powder.The powder can be dispersed into a fluid that is either reactive,photochemically sensitive, or also contains that ability to convert tosilicon carbide. Although the discussion herein may refer to siliconcarbide, other pre-ceramic polymer materials may be employed. Resins andother preceramic polymers may be chosen to make silicon carbide, siliconnitride, silicon carbide nitride, and silicon oxy-carbide as the primaryresins. In certain embodiments, derivatives of the polymers may bemodified with boron or aluminum to provide additional properties.Functionalization of the powder is a different step than buildup andcuring. In addition to functionalizing the material, resin is selectedto convert to a ceramic of choice.

Process 400 may optionally include suspending the functionalizedinorganic particles in the resin at block 415. Suspension of thefunctionalized particles at block 415 may include uniform distributionof the particles into a preceramic polymer that is configured to convertto a ceramic phase, such as polycarbosilane.

While this disclosure has been particularly shown and described withreferences to exemplary embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the claimedembodiments.

What is claimed is:
 1. A method for additive manufacturing of a ceramicstructure, the method comprising: providing a resin, the resin includinga preceramic polymer and inorganic ceramic filler particles dispersed inthe preceramic polymer, wherein the preceramic polymer is configured toconvert to a ceramic phase, and wherein the inorganic ceramic fillerparticles are functionalized with a reactive group and configured toconvert to the ceramic phase; and applying an energy source to the resinto create at least one layer of the ceramic phase from the resin.
 2. Themethod of claim 1, wherein the preceramic polymer is polycarbosilane. 3.The method of claim 1, wherein the ceramic phase is silicon carbide. 4.The method of claim 1, wherein the inorganic ceramic filler particlesare functionalized with a reactive group.
 5. The method of claim 1,wherein the energy source is a laser source for curing at least one ofthe preceramic polymer and ceramic filler particles.
 6. The method ofclaim 1, wherein the resin is provided in a bath for additivemanufacturing.
 7. The method of claim 1, wherein the inorganic ceramicfiller particles include functional groups configured to decompose and aceramic phase, wherein the ceramic phase remains during fabrication. 8.The method of claim 1, wherein applying an energy source to the resinincludes free form fabrication of a three-dimensional article formed ofsilicon carbide.
 9. The method of claim 1, further comprising processingan article formed by the layer and one or more additional layers,wherein processing includes exposure of layers to at least one ofthermal, plasma, microwave and electromagnetic radiation, and curingmethods in general.
 10. A system for resin based additive manufacturingof ceramics, the system comprising: a bath configured to contain aresin, the resin including a preceramic polymer and inorganic ceramicfiller particles dispersed in the preceramic polymer, wherein thepreceramic polymer is configured to convert to a ceramic phase, whereinthe inorganic ceramic filler particles are functionalized with areactive group and configured to convert to the ceramic phase; an energysource proximate to the bath; and a controller coupled to the energysource and configured to apply the energy source to the resin to createat least one layer of the ceramic phase from the resin.
 11. The systemof claim 10, wherein the preceramic polymer is polycarbosilane.
 12. Thesystem of claim 10, wherein the ceramic phase is silicon carbide. 13.The system of claim 10, wherein the inorganic ceramic filler particlesare functionalized with a reactive group.
 14. The system of claim 10,wherein the energy source is a laser source for curing at least one ofthe preceramic polymer and ceramic filler particles.
 15. The system ofclaim 10, wherein the resin is provided in a bath for additivemanufacturing.
 16. The system of claim 10, wherein the inorganic ceramicfiller particles include functional groups configured to decompose and aceramic phase, wherein the ceramic phase remains during fabrication. 17.The system of claim 10, wherein applying an energy source to the resinincludes free form fabrication of a three-dimensional article formed ofsilicon carbide.
 18. The system of claim 10, further comprisingprocessing an article formed by the layer and one or more additionallayers, wherein processing includes exposure of layers to at least oneof thermal, plasma, microwave and electromagnetic radiation, and curingmethods in general.
 19. A resin for additive manufacturing of ceramics,the resin comprising: a preceramic polymer wherein the preceramicpolymer is configured to convert to a ceramic phase; and inorganicceramic filler particles dispersed in the preceramic polymer, whereinthe inorganic ceramic filler particles are functionalized with areactive group and configured to convert to the ceramic phase.
 20. Theresin of claim 1, wherein the ceramic phase is silicon carbide.